1. Field of the Invention
The present invention relates to a projector.
2. Description of the Related Art
In these days, data projectors are used in many cases which projects an image displayed on the screen of a personal computer, an image carried on a video signal, and furthermore, an image carried on image data stored in a memory card or the like.
Many of the data projectors have a construction in which light emitted from a compact high-intensity light source, for which a metal halide lamp or extra-high pressure mercury vapor lamp is used, is converted into light beams of three primary colors by a color filter so as to be irradiated onto a display device such as a liquid crystal display device or a DMD (digital micromirror device) by a light source side optical system, and a image light beam that has passed through or been reflected by the display device is projected onto a screen via units or groups of lenses which constitute a projection side optical system having a zooming function.
In the projectors like this, there may occur a case where a keystone distortion in a projected image by a distance to the screen, a tilt angle of the screen and a projection angle, and in order to correct the keystone distortion (keystoning correction), a distance to the screen, a tilt angle of the screen and a projection angle need to be measured accurately. To make this possible, a distance measuring device needs to be provide on the projector.